- renamed irop_flag_side_effect to irop_flag_uses_memory

[libfirm] / ir / be / ia32 / ia32_emitter.c

/*
 * Copyright (C) 1995-2007 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @brief       This file implements the ia32 node emitter.
 * @author      Christian Wuerdig, Matthias Braun
 * @version     $Id$
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <limits.h>

#include "xmalloc.h"
#include "tv.h"
#include "iredges.h"
#include "debug.h"
#include "irgwalk.h"
#include "irprintf.h"
#include "irop_t.h"
#include "irargs_t.h"
#include "irprog_t.h"
#include "iredges_t.h"
#include "execfreq.h"
#include "error.h"
#include "raw_bitset.h"
#include "dbginfo.h"

#include "../besched_t.h"
#include "../benode_t.h"
#include "../beabi.h"
#include "../be_dbgout.h"
#include "../beemitter.h"
#include "../begnuas.h"
#include "../beirg_t.h"

#include "ia32_emitter.h"
#include "gen_ia32_emitter.h"
#include "gen_ia32_regalloc_if.h"
#include "ia32_nodes_attr.h"
#include "ia32_new_nodes.h"
#include "ia32_map_regs.h"
#include "ia32_architecture.h"
#include "bearch_ia32_t.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

#define BLOCK_PREFIX ".L"

#define SNPRINTF_BUF_LEN 128

static const arch_env_t *arch_env;
static const ia32_isa_t *isa;
static ia32_code_gen_t  *cg;

/**
 * Returns the register at in position pos.
 */
static const arch_register_t *get_in_reg(const ir_node *irn, int pos)
{
        ir_node               *op;
        const arch_register_t *reg = NULL;

        assert(get_irn_arity(irn) > pos && "Invalid IN position");

        /* The out register of the operator at position pos is the
           in register we need. */
        op = get_irn_n(irn, pos);

        reg = arch_get_irn_register(arch_env, op);

        assert(reg && "no in register found");

        if(reg == &ia32_gp_regs[REG_GP_NOREG])
                panic("trying to emit noreg for %+F input %d", irn, pos);

        /* in case of unknown register: just return a valid register */
        if (reg == &ia32_gp_regs[REG_GP_UKNWN]) {
                const arch_register_req_t *req;

                /* ask for the requirements */
                req = arch_get_register_req(arch_env, irn, pos);

                if (arch_register_req_is(req, limited)) {
                        /* in case of limited requirements: get the first allowed register */
                        unsigned idx = rbitset_next(req->limited, 0, 1);
                        reg = arch_register_for_index(req->cls, idx);
                } else {
                        /* otherwise get first register in class */
                        reg = arch_register_for_index(req->cls, 0);
                }
        }

        return reg;
}

/**
 * Returns the register at out position pos.
 */
static const arch_register_t *get_out_reg(const ir_node *irn, int pos)
{
        ir_node               *proj;
        const arch_register_t *reg = NULL;

        /* 1st case: irn is not of mode_T, so it has only                 */
        /*           one OUT register -> good                             */
        /* 2nd case: irn is of mode_T -> collect all Projs and ask the    */
        /*           Proj with the corresponding projnum for the register */

        if (get_irn_mode(irn) != mode_T) {
                assert(pos == 0);
                reg = arch_get_irn_register(arch_env, irn);
        } else if (is_ia32_irn(irn)) {
                reg = get_ia32_out_reg(irn, pos);
        } else {
                const ir_edge_t *edge;

                foreach_out_edge(irn, edge) {
                        proj = get_edge_src_irn(edge);
                        assert(is_Proj(proj) && "non-Proj from mode_T node");
                        if (get_Proj_proj(proj) == pos) {
                                reg = arch_get_irn_register(arch_env, proj);
                                break;
                        }
                }
        }

        assert(reg && "no out register found");
        return reg;
}

/**
 * Add a number to a prefix. This number will not be used a second time.
 */
static char *get_unique_label(char *buf, size_t buflen, const char *prefix)
{
        static unsigned long id = 0;
        snprintf(buf, buflen, "%s%lu", prefix, ++id);
        return buf;
}

/*************************************************************
 *             _       _    __   _          _
 *            (_)     | |  / _| | |        | |
 *  _ __  _ __ _ _ __ | |_| |_  | |__   ___| |_ __   ___ _ __
 * | '_ \| '__| | '_ \| __|  _| | '_ \ / _ \ | '_ \ / _ \ '__|
 * | |_) | |  | | | | | |_| |   | | | |  __/ | |_) |  __/ |
 * | .__/|_|  |_|_| |_|\__|_|   |_| |_|\___|_| .__/ \___|_|
 * | |                                       | |
 * |_|                                       |_|
 *************************************************************/

static void emit_8bit_register(const arch_register_t *reg)
{
        const char *reg_name = arch_register_get_name(reg);

        be_emit_char('%');
        be_emit_char(reg_name[1]);
        be_emit_char('l');
}

static void emit_16bit_register(const arch_register_t *reg)
{
        const char *reg_name = ia32_get_mapped_reg_name(isa->regs_16bit, reg);

        be_emit_char('%');
        be_emit_string(reg_name);
}

static void emit_register(const arch_register_t *reg, const ir_mode *mode)
{
        const char *reg_name;

        if(mode != NULL) {
                int size = get_mode_size_bits(mode);
                if(size == 8) {
                        emit_8bit_register(reg);
                        return;
                } else if(size == 16) {
                        emit_16bit_register(reg);
                        return;
                } else {
                        assert(mode_is_float(mode) || size == 32);
                }
        }

        reg_name = arch_register_get_name(reg);

        be_emit_char('%');
        be_emit_string(reg_name);
}

void ia32_emit_source_register(const ir_node *node, int pos)
{
        const arch_register_t *reg      = get_in_reg(node, pos);

        emit_register(reg, NULL);
}

static void emit_ia32_Immediate(const ir_node *node);

void ia32_emit_8bit_source_register_or_immediate(const ir_node *node, int pos)
{
        const arch_register_t *reg;
        ir_node               *in = get_irn_n(node, pos);
        if(is_ia32_Immediate(in)) {
                emit_ia32_Immediate(in);
                return;
        }

        reg = get_in_reg(node, pos);
        emit_8bit_register(reg);
}

void ia32_emit_dest_register(const ir_node *node, int pos)
{
        const arch_register_t *reg  = get_out_reg(node, pos);

        emit_register(reg, NULL);
}

void ia32_emit_8bit_dest_register(const ir_node *node, int pos)
{
        const arch_register_t *reg  = get_out_reg(node, pos);

        emit_register(reg, mode_Bu);
}

void ia32_emit_x87_register(const ir_node *node, int pos)
{
        const ia32_x87_attr_t *attr = get_ia32_x87_attr_const(node);

        assert(pos < 3);
        be_emit_char('%');
        be_emit_string(attr->x87[pos]->name);
}

static void ia32_emit_mode_suffix_mode(const ir_mode *mode)
{
        if(mode_is_float(mode)) {
                switch(get_mode_size_bits(mode)) {
                case 32: be_emit_char('s'); return;
                case 64: be_emit_char('l'); return;
                case 80:
                case 96: be_emit_char('t'); return;
                }
        } else {
                assert(mode_is_int(mode) || mode_is_reference(mode));
                switch(get_mode_size_bits(mode)) {
                case 64: be_emit_cstring("ll"); return;
                                 /* gas docu says q is the suffix but gcc, objdump and icc use
                                        ll apparently */
                case 32: be_emit_char('l'); return;
                case 16: be_emit_char('w'); return;
                case 8:  be_emit_char('b'); return;
                }
        }
        panic("Can't output mode_suffix for %+F\n", mode);
}

void ia32_emit_mode_suffix(const ir_node *node)
{
        ir_mode *mode = get_ia32_ls_mode(node);
        if(mode == NULL)
                mode = mode_Iu;

        ia32_emit_mode_suffix_mode(mode);
}

void ia32_emit_x87_mode_suffix(const ir_node *node)
{
        ir_mode *mode = get_ia32_ls_mode(node);
        assert(mode != NULL);
        /* we only need to emit the mode on address mode */
        if(get_ia32_op_type(node) != ia32_Normal)
                ia32_emit_mode_suffix_mode(mode);
}

static
char get_xmm_mode_suffix(ir_mode *mode)
{
        assert(mode_is_float(mode));
        switch(get_mode_size_bits(mode)) {
        case 32:
                return 's';
        case 64:
                return 'd';
        default:
                assert(0);
        }
        return '%';
}

void ia32_emit_xmm_mode_suffix(const ir_node *node)
{
        ir_mode *mode = get_ia32_ls_mode(node);
        assert(mode != NULL);
        be_emit_char('s');
        be_emit_char(get_xmm_mode_suffix(mode));
}

void ia32_emit_xmm_mode_suffix_s(const ir_node *node)
{
        ir_mode *mode = get_ia32_ls_mode(node);
        assert(mode != NULL);
        be_emit_char(get_xmm_mode_suffix(mode));
}

void ia32_emit_extend_suffix(const ir_mode *mode)
{
        if(get_mode_size_bits(mode) == 32)
                return;
        if(mode_is_signed(mode)) {
                be_emit_char('s');
        } else {
                be_emit_char('z');
        }
}

static
void ia32_emit_function_object(const char *name)
{
        switch (be_gas_flavour) {
        case GAS_FLAVOUR_NORMAL:
                be_emit_cstring("\t.type\t");
                be_emit_string(name);
                be_emit_cstring(", @function\n");
                be_emit_write_line();
                break;
        case GAS_FLAVOUR_MINGW:
                be_emit_cstring("\t.def\t");
                be_emit_string(name);
                be_emit_cstring(";\t.scl\t2;\t.type\t32;\t.endef\n");
                be_emit_write_line();
                break;
        default:
                break;
        }
}

static
void ia32_emit_function_size(const char *name)
{
        switch (be_gas_flavour) {
        case GAS_FLAVOUR_NORMAL:
                be_emit_cstring("\t.size\t");
                be_emit_string(name);
                be_emit_cstring(", .-");
                be_emit_string(name);
                be_emit_char('\n');
                be_emit_write_line();
                break;
        default:
                break;
        }
}


void ia32_emit_source_register_or_immediate(const ir_node *node, int pos)
{
        ir_node *in = get_irn_n(node, pos);
        if(is_ia32_Immediate(in)) {
                emit_ia32_Immediate(in);
        } else {
                const ir_mode         *mode = get_ia32_ls_mode(node);
                const arch_register_t *reg  = get_in_reg(node, pos);
                emit_register(reg, mode);
        }
}

/**
 * Emits registers and/or address mode of a binary operation.
 */
void ia32_emit_binop(const ir_node *node) {
        const ir_node         *right_op  = get_irn_n(node, n_ia32_binary_right);
        const ir_mode         *mode      = get_ia32_ls_mode(node);
        const arch_register_t *reg_left;

        switch(get_ia32_op_type(node)) {
        case ia32_Normal:
                reg_left = get_in_reg(node, n_ia32_binary_left);
                if(is_ia32_Immediate(right_op)) {
                        emit_ia32_Immediate(right_op);
                        be_emit_cstring(", ");
                        emit_register(reg_left, mode);
                        break;
                } else {
                        const arch_register_t *reg_right
                                = get_in_reg(node, n_ia32_binary_right);
                        emit_register(reg_right, mode);
                        be_emit_cstring(", ");
                        emit_register(reg_left, mode);
                }
                break;
        case ia32_AddrModeS:
                if(is_ia32_Immediate(right_op)) {
                        emit_ia32_Immediate(right_op);
                        be_emit_cstring(", ");
                        ia32_emit_am(node);
                } else {
                        reg_left = get_in_reg(node, n_ia32_binary_left);
                        ia32_emit_am(node);
                        be_emit_cstring(", ");
                        emit_register(reg_left, mode);
                }
                break;
        case ia32_AddrModeD:
                panic("DestMode can't be output by %%binop anymore");
                break;
        default:
                assert(0 && "unsupported op type");
        }
}

/**
 * Emits registers and/or address mode of a binary operation.
 */
void ia32_emit_x87_binop(const ir_node *node) {
        switch(get_ia32_op_type(node)) {
                case ia32_Normal:
                        {
                                const ia32_x87_attr_t *x87_attr = get_ia32_x87_attr_const(node);
                                const arch_register_t *in1      = x87_attr->x87[0];
                                const arch_register_t *in2      = x87_attr->x87[1];
                                const arch_register_t *out      = x87_attr->x87[2];
                                const arch_register_t *in;

                                in  = out ? ((out == in2) ? in1 : in2) : in2;
                                out = out ? out : in1;

                                be_emit_char('%');
                                be_emit_string(arch_register_get_name(in));
                                be_emit_cstring(", %");
                                be_emit_string(arch_register_get_name(out));
                        }
                        break;
                case ia32_AddrModeS:
                        ia32_emit_am(node);
                        break;
                case ia32_AddrModeD:
                default:
                        assert(0 && "unsupported op type");
        }
}

void ia32_emit_am_or_dest_register(const ir_node *node,
                                   int pos) {
        if(get_ia32_op_type(node) == ia32_Normal) {
                ia32_emit_dest_register(node, pos);
        } else {
                assert(get_ia32_op_type(node) == ia32_AddrModeD);
                ia32_emit_am(node);
        }
}

/**
 * Emits registers and/or address mode of a unary operation.
 */
void ia32_emit_unop(const ir_node *node, int pos) {
        const ir_node *op;

        switch(get_ia32_op_type(node)) {
        case ia32_Normal:
                op = get_irn_n(node, pos);
                if (is_ia32_Immediate(op)) {
                        emit_ia32_Immediate(op);
                } else {
                        ia32_emit_source_register(node, pos);
                }
                break;
        case ia32_AddrModeS:
        case ia32_AddrModeD:
                ia32_emit_am(node);
                break;
        default:
                assert(0 && "unsupported op type");
        }
}

/**
 * Emits address mode.
 */
void ia32_emit_am(const ir_node *node) {
        ir_entity *ent       = get_ia32_am_sc(node);
        int        offs      = get_ia32_am_offs_int(node);
        ir_node   *base      = get_irn_n(node, 0);
        int        has_base  = !is_ia32_NoReg_GP(base);
        ir_node   *index     = get_irn_n(node, 1);
        int        has_index = !is_ia32_NoReg_GP(index);

        /* just to be sure... */
        assert(!is_ia32_use_frame(node) || get_ia32_frame_ent(node) != NULL);

        /* emit offset */
        if (ent != NULL) {
                ident *id;

                set_entity_backend_marked(ent, 1);
                id = get_entity_ld_ident(ent);
                if (is_ia32_am_sc_sign(node))
                        be_emit_char('-');
                be_emit_ident(id);

                if(get_entity_owner(ent) == get_tls_type()) {
                        if (get_entity_visibility(ent) == visibility_external_allocated) {
                                be_emit_cstring("@INDNTPOFF");
                        } else {
                                be_emit_cstring("@NTPOFF");
                        }
                }
        }

        if(offs != 0) {
                if(ent != NULL) {
                        be_emit_irprintf("%+d", offs);
                } else {
                        be_emit_irprintf("%d", offs);
                }
        }

        if (has_base || has_index) {
                be_emit_char('(');

                /* emit base */
                if (has_base) {
                        const arch_register_t *reg = get_in_reg(node, n_ia32_base);
                        emit_register(reg, NULL);
                }

                /* emit index + scale */
                if (has_index) {
                        const arch_register_t *reg = get_in_reg(node, n_ia32_index);
                        int scale;
                        be_emit_char(',');
                        emit_register(reg, NULL);

                        scale = get_ia32_am_scale(node);
                        if (scale > 0) {
                                be_emit_irprintf(",%d", 1 << get_ia32_am_scale(node));
                        }
                }
                be_emit_char(')');
        }

        /* special case if nothing is set */
        if(ent == NULL && offs == 0 && !has_base && !has_index) {
                be_emit_char('0');
        }
}

static void emit_ia32_IMul(const ir_node *node)
{
        ir_node               *left    = get_irn_n(node, n_ia32_IMul_left);
        const arch_register_t *out_reg = get_out_reg(node, pn_ia32_IMul_res);

        be_emit_cstring("\timul");
        ia32_emit_mode_suffix(node);
        be_emit_char(' ');

        ia32_emit_binop(node);

        /* do we need the 3-address form? */
        if(is_ia32_NoReg_GP(left) ||
                        get_in_reg(node, n_ia32_IMul_left) != out_reg) {
                be_emit_cstring(", ");
                emit_register(out_reg, get_ia32_ls_mode(node));
        }
        be_emit_finish_line_gas(node);
}

/*************************************************
 *                 _ _                         _
 *                (_) |                       | |
 *   ___ _ __ ___  _| |_    ___ ___  _ __   __| |
 *  / _ \ '_ ` _ \| | __|  / __/ _ \| '_ \ / _` |
 * |  __/ | | | | | | |_  | (_| (_) | | | | (_| |
 *  \___|_| |_| |_|_|\__|  \___\___/|_| |_|\__,_|
 *
 *************************************************/

#undef IA32_DO_EMIT
#define IA32_DO_EMIT(irn) ia32_fprintf_format(F, irn, cmd_buf, cmnt_buf)

/*
 * coding of conditions
 */
struct cmp2conditon_t {
        const char *name;
        int         num;
};

/*
 * positive conditions for signed compares
 */
static const struct cmp2conditon_t cmp2condition_s[] = {
        { NULL,              pn_Cmp_False },  /* always false */
        { "e",               pn_Cmp_Eq },     /* == */
        { "l",               pn_Cmp_Lt },     /* < */
        { "le",              pn_Cmp_Le },     /* <= */
        { "g",               pn_Cmp_Gt },     /* > */
        { "ge",              pn_Cmp_Ge },     /* >= */
        { "ne",              pn_Cmp_Lg },     /* != */
        { NULL,              pn_Cmp_Leg},     /* always true */
};

/*
 * positive conditions for unsigned compares
 */
static const struct cmp2conditon_t cmp2condition_u[] = {
        { NULL,              pn_Cmp_False },  /* always false */
        { "e",               pn_Cmp_Eq },     /* == */
        { "b",               pn_Cmp_Lt },     /* < */
        { "be",              pn_Cmp_Le },     /* <= */
        { "a",               pn_Cmp_Gt },     /* > */
        { "ae",              pn_Cmp_Ge },     /* >= */
        { "ne",              pn_Cmp_Lg },     /* != */
        { NULL,              pn_Cmp_Leg },   /* always true  */
};

enum {
        ia32_pn_Cmp_unsigned = 0x1000,
        ia32_pn_Cmp_float    = 0x2000,
};

/**
 * walks up a tree of copies/perms/spills/reloads to find the original value
 * that is moved around
 */
static ir_node *find_original_value(ir_node *node)
{
        inc_irg_visited(current_ir_graph);
        while(1) {
                mark_irn_visited(node);
                if(be_is_Copy(node)) {
                        node = be_get_Copy_op(node);
                } else if(be_is_CopyKeep(node)) {
                        node = be_get_CopyKeep_op(node);
                } else if(is_Proj(node)) {
                        ir_node *pred = get_Proj_pred(node);
                        if(be_is_Perm(pred)) {
                                node = get_irn_n(pred, get_Proj_proj(node));
                        } else if(be_is_MemPerm(pred)) {
                                node = get_irn_n(pred, get_Proj_proj(node) + 1);
                        } else if(is_ia32_Load(pred)) {
                                node = get_irn_n(pred, n_ia32_Load_mem);
                        } else {
                                return node;
                        }
                } else if(is_ia32_Store(node)) {
                        node = get_irn_n(node, n_ia32_Store_val);
                } else if(is_Phi(node)) {
                        int i, arity;
                        arity = get_irn_arity(node);
                        for(i = 0; i < arity; ++i) {
                                ir_node *in = get_irn_n(node, i);
                                if(irn_visited(in))
                                        continue;
                                node = in;
                                break;
                        }
                        assert(i < arity);
                } else {
                        return node;
                }
        }
}

static int determine_final_pnc(const ir_node *node, int flags_pos,
                               int pnc)
{
        ir_node           *flags = get_irn_n(node, flags_pos);
        const ia32_attr_t *flags_attr;
        flags = skip_Proj(flags);

        if(is_ia32_Sahf(flags)) {
                ir_node *cmp = get_irn_n(flags, n_ia32_Sahf_val);
                if(!(is_ia32_FucomFnstsw(cmp) || is_ia32_FucompFnstsw(cmp)
                                || is_ia32_FucomppFnstsw(cmp) || is_ia32_FtstFnstsw(cmp))) {
                        cmp = find_original_value(cmp);
                        assert(is_ia32_FucomFnstsw(cmp) || is_ia32_FucompFnstsw(cmp)
                               || is_ia32_FucomppFnstsw(cmp) || is_ia32_FtstFnstsw(cmp));
                }

                flags_attr = get_ia32_attr_const(cmp);
                if(flags_attr->data.ins_permuted)
                        pnc = get_mirrored_pnc(pnc);
                pnc |= ia32_pn_Cmp_float;
        } else if(is_ia32_Ucomi(flags) || is_ia32_Fucomi(flags)
                        || is_ia32_Fucompi(flags)) {
                flags_attr = get_ia32_attr_const(flags);

                if(flags_attr->data.ins_permuted)
                        pnc = get_mirrored_pnc(pnc);
                pnc |= ia32_pn_Cmp_float;
        } else {
#if 0
                assert(is_ia32_Cmp(flags) || is_ia32_Test(flags)
                                || is_ia32_Cmp8Bit(flags) || is_ia32_Test8Bit(flags));
#endif
                flags_attr = get_ia32_attr_const(flags);

                if(flags_attr->data.ins_permuted)
                        pnc = get_mirrored_pnc(pnc);
                if(flags_attr->data.cmp_unsigned)
                        pnc |= ia32_pn_Cmp_unsigned;
        }

        return pnc;
}

static void ia32_emit_cmp_suffix(int pnc)
{
        const char        *str;

        if((pnc & ia32_pn_Cmp_float) || (pnc & ia32_pn_Cmp_unsigned)) {
                pnc = pnc & 7;
                assert(cmp2condition_u[pnc].num == pnc);
                str = cmp2condition_u[pnc].name;
        } else {
                pnc = pnc & 7;
                assert(cmp2condition_s[pnc].num == pnc);
                str = cmp2condition_s[pnc].name;
        }

        be_emit_string(str);
}

void ia32_emit_cmp_suffix_node(const ir_node *node,
                               int flags_pos)
{
        const ia32_attr_t *attr = get_ia32_attr_const(node);

        pn_Cmp pnc = get_ia32_condcode(node);

        pnc = determine_final_pnc(node, flags_pos, pnc);
        if(attr->data.ins_permuted) {
                if(pnc & ia32_pn_Cmp_float) {
                        pnc = get_negated_pnc(pnc, mode_F);
                } else {
                        pnc = get_negated_pnc(pnc, mode_Iu);
                }
        }

        ia32_emit_cmp_suffix(pnc);
}

/**
 * Returns the target block for a control flow node.
 */
static
ir_node *get_cfop_target_block(const ir_node *irn) {
        return get_irn_link(irn);
}

/**
 * Emits a block label for the given block.
 */
static
void ia32_emit_block_name(const ir_node *block)
{
        if (has_Block_label(block)) {
                be_emit_string(be_gas_label_prefix());
                be_emit_irprintf("%u", (unsigned)get_Block_label(block));
        } else {
                be_emit_cstring(BLOCK_PREFIX);
                be_emit_irprintf("%d", get_irn_node_nr(block));
        }
}

/**
 * Emits the target label for a control flow node.
 */
static void ia32_emit_cfop_target(const ir_node *node)
{
        ir_node *block = get_cfop_target_block(node);

        ia32_emit_block_name(block);
}

/** Return the next block in Block schedule */
static ir_node *next_blk_sched(const ir_node *block)
{
        return get_irn_link(block);
}

/**
 * Returns the Proj with projection number proj and NOT mode_M
 */
static ir_node *get_proj(const ir_node *node, long proj) {
        const ir_edge_t *edge;
        ir_node         *src;

        assert(get_irn_mode(node) == mode_T && "expected mode_T node");

        foreach_out_edge(node, edge) {
                src = get_edge_src_irn(edge);

                assert(is_Proj(src) && "Proj expected");
                if (get_irn_mode(src) == mode_M)
                        continue;

                if (get_Proj_proj(src) == proj)
                        return src;
        }
        return NULL;
}

/**
 * Emits the jump sequence for a conditional jump (cmp + jmp_true + jmp_false)
 */
static void emit_ia32_Jcc(const ir_node *node)
{
        const ir_node *proj_true;
        const ir_node *proj_false;
        const ir_node *block;
        const ir_node *next_block;
        pn_Cmp         pnc = get_ia32_condcode(node);

        pnc = determine_final_pnc(node, 0, pnc);

        /* get both Projs */
        proj_true = get_proj(node, pn_ia32_Jcc_true);
        assert(proj_true && "Jcc without true Proj");

        proj_false = get_proj(node, pn_ia32_Jcc_false);
        assert(proj_false && "Jcc without false Proj");

        block      = get_nodes_block(node);
        next_block = next_blk_sched(block);

        if (get_cfop_target_block(proj_true) == next_block) {
                /* exchange both proj's so the second one can be omitted */
                const ir_node *t = proj_true;

                proj_true  = proj_false;
                proj_false = t;
                if(pnc & ia32_pn_Cmp_float) {
                        pnc = get_negated_pnc(pnc, mode_F);
                } else {
                        pnc = get_negated_pnc(pnc, mode_Iu);
                }
        }

        if (pnc & ia32_pn_Cmp_float) {
                /* Some floating point comparisons require a test of the parity flag,
                 * which indicates that the result is unordered */
                switch (pnc & 15) {
                        case pn_Cmp_Uo:
                                be_emit_cstring("\tjp ");
                                ia32_emit_cfop_target(proj_true);
                                be_emit_finish_line_gas(proj_true);
                                break;

                        case pn_Cmp_Leg:
                                be_emit_cstring("\tjnp ");
                                ia32_emit_cfop_target(proj_true);
                                be_emit_finish_line_gas(proj_true);
                                break;

                        case pn_Cmp_Eq:
                        case pn_Cmp_Lt:
                        case pn_Cmp_Le:
                                be_emit_cstring("\tjp ");
                                ia32_emit_cfop_target(proj_false);
                                be_emit_finish_line_gas(proj_false);
                                goto emit_jcc;

                        case pn_Cmp_Ug:
                        case pn_Cmp_Uge:
                        case pn_Cmp_Ne:
                                be_emit_cstring("\tjp ");
                                ia32_emit_cfop_target(proj_true);
                                be_emit_finish_line_gas(proj_true);
                                goto emit_jcc;

                        default:
                                goto emit_jcc;
                }
        } else {
emit_jcc:
                be_emit_cstring("\tj");
                ia32_emit_cmp_suffix(pnc);
                be_emit_char(' ');
                ia32_emit_cfop_target(proj_true);
                be_emit_finish_line_gas(proj_true);
        }

        /* the second Proj might be a fallthrough */
        if (get_cfop_target_block(proj_false) != next_block) {
                be_emit_cstring("\tjmp ");
                ia32_emit_cfop_target(proj_false);
                be_emit_finish_line_gas(proj_false);
        } else {
                be_emit_cstring("\t/* fallthrough to ");
                ia32_emit_cfop_target(proj_false);
                be_emit_cstring(" */");
                be_emit_finish_line_gas(proj_false);
        }
}

static void emit_ia32_CMov(const ir_node *node)
{
        const ia32_attr_t     *attr         = get_ia32_attr_const(node);
        int                    ins_permuted = attr->data.ins_permuted;
        const arch_register_t *out          = arch_get_irn_register(arch_env, node);
        pn_Cmp                 pnc          = get_ia32_condcode(node);
        const arch_register_t *in_true;
        const arch_register_t *in_false;

        pnc = determine_final_pnc(node, n_ia32_CMov_eflags, pnc);

        in_true  = arch_get_irn_register(arch_env,
                                         get_irn_n(node, n_ia32_CMov_val_true));
        in_false = arch_get_irn_register(arch_env,
                                         get_irn_n(node, n_ia32_CMov_val_false));

        /* should be same constraint fullfilled? */
        if(out == in_false) {
                /* yes -> nothing to do */
        } else if(out == in_true) {
                const arch_register_t *tmp;

                assert(get_ia32_op_type(node) == ia32_Normal);

                ins_permuted = !ins_permuted;

                tmp      = in_true;
                in_true  = in_false;
                in_false = tmp;
        } else {
                /* we need a mov */
                be_emit_cstring("\tmovl ");
                emit_register(in_false, NULL);
                be_emit_cstring(", ");
                emit_register(out, NULL);
                be_emit_finish_line_gas(node);
        }

        if(ins_permuted) {
                if(pnc & ia32_pn_Cmp_float) {
                        pnc = get_negated_pnc(pnc, mode_F);
                } else {
                        pnc = get_negated_pnc(pnc, mode_Iu);
                }
        }

        /* TODO: handling of Nans isn't correct yet */

        be_emit_cstring("\tcmov");
        ia32_emit_cmp_suffix(pnc);
        be_emit_char(' ');
        if(get_ia32_op_type(node) == ia32_AddrModeS) {
                ia32_emit_am(node);
        } else {
                emit_register(in_true, get_ia32_ls_mode(node));
        }
        be_emit_cstring(", ");
        emit_register(out, get_ia32_ls_mode(node));
        be_emit_finish_line_gas(node);
}

/*********************************************************
 *                 _ _       _
 *                (_) |     (_)
 *   ___ _ __ ___  _| |_     _ _   _ _ __ ___  _ __  ___
 *  / _ \ '_ ` _ \| | __|   | | | | | '_ ` _ \| '_ \/ __|
 * |  __/ | | | | | | |_    | | |_| | | | | | | |_) \__ \
 *  \___|_| |_| |_|_|\__|   | |\__,_|_| |_| |_| .__/|___/
 *                         _/ |               | |
 *                        |__/                |_|
 *********************************************************/

/* jump table entry (target and corresponding number) */
typedef struct _branch_t {
        ir_node *target;
        int      value;
} branch_t;

/* jump table for switch generation */
typedef struct _jmp_tbl_t {
        ir_node  *defProj;         /**< default target */
        long      min_value;       /**< smallest switch case */
        long      max_value;       /**< largest switch case */
        long      num_branches;    /**< number of jumps */
        char     *label;           /**< label of the jump table */
        branch_t *branches;        /**< jump array */
} jmp_tbl_t;

/**
 * Compare two variables of type branch_t. Used to sort all switch cases
 */
static
int ia32_cmp_branch_t(const void *a, const void *b) {
        branch_t *b1 = (branch_t *)a;
        branch_t *b2 = (branch_t *)b;

        if (b1->value <= b2->value)
                return -1;
        else
                return 1;
}

/**
 * Emits code for a SwitchJmp (creates a jump table if
 * possible otherwise a cmp-jmp cascade). Port from
 * cggg ia32 backend
 */
static void emit_ia32_SwitchJmp(const ir_node *node)
{
        unsigned long       interval;
        int                 last_value, i;
        long                pnc;
        long                default_pn;
        jmp_tbl_t           tbl;
        ir_node            *proj;
        const ir_edge_t    *edge;

        /* fill the table structure */
        tbl.label        = xmalloc(SNPRINTF_BUF_LEN);
        tbl.label        = get_unique_label(tbl.label, SNPRINTF_BUF_LEN, ".TBL_");
        tbl.defProj      = NULL;
        tbl.num_branches = get_irn_n_edges(node) - 1;
        tbl.branches     = xcalloc(tbl.num_branches, sizeof(tbl.branches[0]));
        tbl.min_value    = INT_MAX;
        tbl.max_value    = INT_MIN;

        default_pn = get_ia32_condcode(node);
        i = 0;
        /* go over all proj's and collect them */
        foreach_out_edge(node, edge) {
                proj = get_edge_src_irn(edge);
                assert(is_Proj(proj) && "Only proj allowed at SwitchJmp");

                pnc = get_Proj_proj(proj);

                /* check for default proj */
                if (pnc == default_pn) {
                        assert(tbl.defProj == NULL && "found two default Projs at SwitchJmp");
                        tbl.defProj = proj;
                } else {
                        tbl.min_value = pnc < tbl.min_value ? pnc : tbl.min_value;
                        tbl.max_value = pnc > tbl.max_value ? pnc : tbl.max_value;

                        /* create branch entry */
                        tbl.branches[i].target = proj;
                        tbl.branches[i].value  = pnc;
                        ++i;
                }

        }
        assert(i == tbl.num_branches);

        /* sort the branches by their number */
        qsort(tbl.branches, tbl.num_branches, sizeof(tbl.branches[0]), ia32_cmp_branch_t);

        /* two-complement's magic make this work without overflow */
        interval = tbl.max_value - tbl.min_value;

        /* emit the table */
        be_emit_cstring("\tcmpl $");
        be_emit_irprintf("%u, ", interval);
        ia32_emit_source_register(node, 0);
        be_emit_finish_line_gas(node);

        be_emit_cstring("\tja ");
        ia32_emit_cfop_target(tbl.defProj);
        be_emit_finish_line_gas(node);

        if (tbl.num_branches > 1) {
                /* create table */
                be_emit_cstring("\tjmp *");
                be_emit_string(tbl.label);
                be_emit_cstring("(,");
                ia32_emit_source_register(node, 0);
                be_emit_cstring(",4)");
                be_emit_finish_line_gas(node);

                be_gas_emit_switch_section(GAS_SECTION_RODATA);
                be_emit_cstring("\t.align 4\n");
                be_emit_write_line();

                be_emit_string(tbl.label);
                be_emit_cstring(":\n");
                be_emit_write_line();

                be_emit_cstring(".long ");
                ia32_emit_cfop_target(tbl.branches[0].target);
                be_emit_finish_line_gas(NULL);

                last_value = tbl.branches[0].value;
                for (i = 1; i < tbl.num_branches; ++i) {
                        while (++last_value < tbl.branches[i].value) {
                                be_emit_cstring(".long ");
                                ia32_emit_cfop_target(tbl.defProj);
                                be_emit_finish_line_gas(NULL);
                        }
                        be_emit_cstring(".long ");
                        ia32_emit_cfop_target(tbl.branches[i].target);
                        be_emit_finish_line_gas(NULL);
                }
                be_gas_emit_switch_section(GAS_SECTION_TEXT);
        } else {
                /* one jump is enough */
                be_emit_cstring("\tjmp ");
                ia32_emit_cfop_target(tbl.branches[0].target);
                be_emit_finish_line_gas(node);
        }

        if (tbl.label)
                free(tbl.label);
        if (tbl.branches)
                free(tbl.branches);
}

/**
 * Emits code for a unconditional jump.
 */
static void emit_Jmp(const ir_node *node)
{
        ir_node *block, *next_block;

        /* for now, the code works for scheduled and non-schedules blocks */
        block = get_nodes_block(node);

        /* we have a block schedule */
        next_block = next_blk_sched(block);
        if (get_cfop_target_block(node) != next_block) {
                be_emit_cstring("\tjmp ");
                ia32_emit_cfop_target(node);
        } else {
                be_emit_cstring("\t/* fallthrough to ");
                ia32_emit_cfop_target(node);
                be_emit_cstring(" */");
        }
        be_emit_finish_line_gas(node);
}

static void emit_ia32_Immediate(const ir_node *node)
{
        const ia32_immediate_attr_t *attr = get_ia32_immediate_attr_const(node);

        be_emit_char('$');
        if(attr->symconst != NULL) {
                ident *id = get_entity_ld_ident(attr->symconst);

                if(attr->sc_sign)
                        be_emit_char('-');
                be_emit_ident(id);
        }
        if(attr->symconst == NULL || attr->offset != 0) {
                if(attr->symconst != NULL) {
                        be_emit_irprintf("%+d", attr->offset);
                } else {
                        be_emit_irprintf("0x%X", attr->offset);
                }
        }
}

/**
 * Emit an inline assembler operand.
 *
 * @param node  the ia32_ASM node
 * @param s     points to the operand (a %c)
 *
 * @return  pointer to the first char in s NOT in the current operand
 */
static const char* emit_asm_operand(const ir_node *node, const char *s)
{
        const ia32_attr_t     *ia32_attr = get_ia32_attr_const(node);
        const ia32_asm_attr_t *attr      = CONST_CAST_IA32_ATTR(ia32_asm_attr_t,
                                                            ia32_attr);
        const arch_register_t *reg;
        const ia32_asm_reg_t  *asm_regs = attr->register_map;
        const ia32_asm_reg_t  *asm_reg;
        const char            *reg_name;
        char                   c;
        char                   modifier = 0;
        int                    num      = -1;
        int                    p;

        assert(*s == '%');
        c = *(++s);

        /* parse modifiers */
        switch(c) {
        case 0:
                ir_fprintf(stderr, "Warning: asm text (%+F) ends with %\n", node);
                be_emit_char('%');
                return s + 1;
        case '%':
                be_emit_char('%');
                return s + 1;
        case 'w':
        case 'b':
        case 'h':
                modifier = c;
                ++s;
                break;
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
                break;
        default:
                ir_fprintf(stderr, "Warning: asm text (%+F) contains unknown modifier "
                           "'%c' for asm op\n", node, c);
                ++s;
                break;
        }

        /* parse number */
        sscanf(s, "%d%n", &num, &p);
        if(num < 0) {
                ir_fprintf(stderr, "Warning: Couldn't parse assembler operand (%+F)\n",
                           node);
                return s;
        } else {
                s += p;
        }

        if(num < 0 || num >= ARR_LEN(asm_regs)) {
                ir_fprintf(stderr, "Error: Custom assembler references invalid "
                           "input/output (%+F)\n", node);
                return s;
        }
        asm_reg = & asm_regs[num];
        assert(asm_reg->valid);

        /* get register */
        if(asm_reg->use_input == 0) {
                reg = get_out_reg(node, asm_reg->inout_pos);
        } else {
                ir_node *pred = get_irn_n(node, asm_reg->inout_pos);

                /* might be an immediate value */
                if(is_ia32_Immediate(pred)) {
                        emit_ia32_Immediate(pred);
                        return s;
                }
                reg = get_in_reg(node, asm_reg->inout_pos);
        }
        if(reg == NULL) {
                ir_fprintf(stderr, "Warning: no register assigned for %d asm op "
                           "(%+F)\n", num, node);
                return s;
        }

        if(asm_reg->memory) {
                be_emit_char('(');
        }

        /* emit it */
        if(modifier != 0) {
                be_emit_char('%');
                switch(modifier) {
                case 'b':
                        reg_name = ia32_get_mapped_reg_name(isa->regs_8bit, reg);
                        break;
                case 'h':
                        reg_name = ia32_get_mapped_reg_name(isa->regs_8bit_high, reg);
                        break;
                case 'w':
                        reg_name = ia32_get_mapped_reg_name(isa->regs_16bit, reg);
                        break;
                default:
                        panic("Invalid asm op modifier");
                }
                be_emit_string(reg_name);
        } else {
                emit_register(reg, asm_reg->mode);
        }

        if(asm_reg->memory) {
                be_emit_char(')');
        }

        return s;
}

/**
 * Emits code for an ASM pseudo op.
 */
static void emit_ia32_Asm(const ir_node *node)
{
        const void            *gen_attr = get_irn_generic_attr_const(node);
        const ia32_asm_attr_t *attr
                = CONST_CAST_IA32_ATTR(ia32_asm_attr_t, gen_attr);
        ident                 *asm_text = attr->asm_text;
        const char            *s        = get_id_str(asm_text);

        be_emit_cstring("# Begin ASM \t");
        be_emit_finish_line_gas(node);

        if (s[0] != '\t')
                be_emit_char('\t');

        while(*s != 0) {
                if(*s == '%') {
                        s = emit_asm_operand(node, s);
                        continue;
                } else {
                        be_emit_char(*s);
                }
                ++s;
        }

        be_emit_char('\n');
        be_emit_write_line();

        be_emit_cstring("# End ASM\n");
        be_emit_write_line();
}

/**********************************
 *   _____                  ____
 *  / ____|                |  _ \
 * | |     ___  _ __  _   _| |_) |
 * | |    / _ \| '_ \| | | |  _ <
 * | |___| (_) | |_) | |_| | |_) |
 *  \_____\___/| .__/ \__, |____/
 *             | |     __/ |
 *             |_|    |___/
 **********************************/

/**
 * Emit movsb/w instructions to make mov count divideable by 4
 */
static void emit_CopyB_prolog(unsigned size) {
        be_emit_cstring("\tcld");
        be_emit_finish_line_gas(NULL);

        switch (size) {
        case 1:
                be_emit_cstring("\tmovsb");
                be_emit_finish_line_gas(NULL);
                break;
        case 2:
                be_emit_cstring("\tmovsw");
                be_emit_finish_line_gas(NULL);
                break;
        case 3:
                be_emit_cstring("\tmovsb");
                be_emit_finish_line_gas(NULL);
                be_emit_cstring("\tmovsw");
                be_emit_finish_line_gas(NULL);
                break;
        }
}

/**
 * Emit rep movsd instruction for memcopy.
 */
static void emit_ia32_CopyB(const ir_node *node)
{
        unsigned size = get_ia32_copyb_size(node);

        emit_CopyB_prolog(size);

        be_emit_cstring("\trep movsd");
        be_emit_finish_line_gas(node);
}

/**
 * Emits unrolled memcopy.
 */
static void emit_ia32_CopyB_i(const ir_node *node)
{
        unsigned size = get_ia32_copyb_size(node);

        emit_CopyB_prolog(size & 0x3);

        size >>= 2;
        while (size--) {
                be_emit_cstring("\tmovsd");
                be_emit_finish_line_gas(NULL);
        }
}



/***************************
 *   _____
 *  / ____|
 * | |     ___  _ ____   __
 * | |    / _ \| '_ \ \ / /
 * | |___| (_) | | | \ V /
 *  \_____\___/|_| |_|\_/
 *
 ***************************/

/**
 * Emit code for conversions (I, FP), (FP, I) and (FP, FP).
 */
static void emit_ia32_Conv_with_FP(const ir_node *node)
{
        ir_mode            *ls_mode = get_ia32_ls_mode(node);
        int                 ls_bits = get_mode_size_bits(ls_mode);

        be_emit_cstring("\tcvt");

        if(is_ia32_Conv_I2FP(node)) {
                if(ls_bits == 32) {
                        be_emit_cstring("si2ss");
                } else {
                        be_emit_cstring("si2sd");
                }
        } else if(is_ia32_Conv_FP2I(node)) {
                if(ls_bits == 32) {
                        be_emit_cstring("ss2si");
                } else {
                        be_emit_cstring("sd2si");
                }
        } else {
                assert(is_ia32_Conv_FP2FP(node));
                if(ls_bits == 32) {
                        be_emit_cstring("sd2ss");
                } else {
                        be_emit_cstring("ss2sd");
                }
        }
        be_emit_char(' ');

        switch(get_ia32_op_type(node)) {
                case ia32_Normal:
                        ia32_emit_source_register(node, n_ia32_unary_op);
                        break;
                case ia32_AddrModeS:
                        ia32_emit_am(node);
                        break;
                default:
                        assert(0 && "unsupported op type for Conv");
        }
        be_emit_cstring(", ");
        ia32_emit_dest_register(node, 0);
        be_emit_finish_line_gas(node);
}

static void emit_ia32_Conv_I2FP(const ir_node *node)
{
        emit_ia32_Conv_with_FP(node);
}

static void emit_ia32_Conv_FP2I(const ir_node *node)
{
        emit_ia32_Conv_with_FP(node);
}

static void emit_ia32_Conv_FP2FP(const ir_node *node)
{
        emit_ia32_Conv_with_FP(node);
}

/**
 * Emits code for an Int conversion.
 */
static void emit_ia32_Conv_I2I(const ir_node *node)
{
        const char            *sign_suffix;
        ir_mode               *smaller_mode = get_ia32_ls_mode(node);
        int                    smaller_bits = get_mode_size_bits(smaller_mode);
        int                    signed_mode;
        const arch_register_t *in_reg, *out_reg;

        assert(!mode_is_float(smaller_mode));
        assert(smaller_bits == 8 || smaller_bits == 16 || smaller_bits == 32);

        signed_mode = mode_is_signed(smaller_mode);
        if(smaller_bits == 32) {
                // this should not happen as it's no convert
                assert(0);
                sign_suffix = "";
        } else {
                sign_suffix = signed_mode ? "s" : "z";
        }

        out_reg = get_out_reg(node, 0);

        switch(get_ia32_op_type(node)) {
                case ia32_Normal:
                        in_reg  = get_in_reg(node, n_ia32_unary_op);

                        if (in_reg  == &ia32_gp_regs[REG_EAX] &&
                                out_reg == &ia32_gp_regs[REG_EAX] &&
                                signed_mode &&
                                smaller_bits == 16)
                        {
                                /* argument and result are both in EAX and */
                                /* signedness is ok: -> use the smaller cwtl opcode */
                                be_emit_cstring("\tcwtl");
                        } else {
                                be_emit_cstring("\tmov");
                                be_emit_string(sign_suffix);
                                ia32_emit_mode_suffix_mode(smaller_mode);
                                be_emit_cstring("l ");
                                emit_register(in_reg, smaller_mode);
                                be_emit_cstring(", ");
                                emit_register(out_reg, NULL);
                        }
                        break;
                case ia32_AddrModeS: {
                        be_emit_cstring("\tmov");
                        be_emit_string(sign_suffix);
                        ia32_emit_mode_suffix_mode(smaller_mode);
                        be_emit_cstring("l ");
                        ia32_emit_am(node);
                        be_emit_cstring(", ");
                        emit_register(out_reg, NULL);
                        break;
                }
                default:
                        assert(0 && "unsupported op type for Conv");
        }
        be_emit_finish_line_gas(node);
}


/*******************************************
 *  _                          _
 * | |                        | |
 * | |__   ___ _ __   ___   __| | ___  ___
 * | '_ \ / _ \ '_ \ / _ \ / _` |/ _ \/ __|
 * | |_) |  __/ | | | (_) | (_| |  __/\__ \
 * |_.__/ \___|_| |_|\___/ \__,_|\___||___/
 *
 *******************************************/

/**
 * Emits a backend call
 */
static void emit_be_Call(const ir_node *node)
{
        ir_entity *ent = be_Call_get_entity(node);

        be_emit_cstring("\tcall ");
        if (ent) {
                set_entity_backend_marked(ent, 1);
                be_emit_string(get_entity_ld_name(ent));
        } else {
                const arch_register_t *reg = get_in_reg(node, be_pos_Call_ptr);
                be_emit_char('*');
                emit_register(reg, NULL);
        }
        be_emit_finish_line_gas(node);
}

/**
 * Emits code to increase stack pointer.
 */
static void emit_be_IncSP(const ir_node *node)
{
        int                    offs = be_get_IncSP_offset(node);
        const arch_register_t *reg  = arch_get_irn_register(arch_env, node);

        if (offs == 0)
                return;

        if (offs > 0) {
                be_emit_cstring("\tsubl $");
                be_emit_irprintf("%u, ", offs);
                emit_register(reg, NULL);
        } else {
                be_emit_cstring("\taddl $");
                be_emit_irprintf("%u, ", -offs);
                emit_register(reg, NULL);
        }
        be_emit_finish_line_gas(node);
}

/**
 * Emits code for Copy/CopyKeep.
 */
static void Copy_emitter(const ir_node *node, const ir_node *op)
{
        const arch_register_t *in  = arch_get_irn_register(arch_env, op);
        const arch_register_t *out = arch_get_irn_register(arch_env, node);
        ir_mode               *mode;

        if(in == out) {
                return;
        }
        if(is_unknown_reg(in))
                return;
        /* copies of vf nodes aren't real... */
        if(arch_register_get_class(in) == &ia32_reg_classes[CLASS_ia32_vfp])
                return;

        mode = get_irn_mode(node);
        if (mode == mode_E) {
                be_emit_cstring("\tmovsd ");
                emit_register(in, NULL);
                be_emit_cstring(", ");
                emit_register(out, NULL);
        } else {
                be_emit_cstring("\tmovl ");
                emit_register(in, NULL);
                be_emit_cstring(", ");
                emit_register(out, NULL);
        }
        be_emit_finish_line_gas(node);
}

static void emit_be_Copy(const ir_node *node)
{
        Copy_emitter(node, be_get_Copy_op(node));
}

static void emit_be_CopyKeep(const ir_node *node)
{
        Copy_emitter(node, be_get_CopyKeep_op(node));
}

/**
 * Emits code for exchange.
 */
static void emit_be_Perm(const ir_node *node)
{
        const arch_register_t *in0, *in1;
        const arch_register_class_t *cls0, *cls1;

        in0 = arch_get_irn_register(arch_env, get_irn_n(node, 0));
        in1 = arch_get_irn_register(arch_env, get_irn_n(node, 1));

        cls0 = arch_register_get_class(in0);
        cls1 = arch_register_get_class(in1);

        assert(cls0 == cls1 && "Register class mismatch at Perm");

        if (cls0 == &ia32_reg_classes[CLASS_ia32_gp]) {
                be_emit_cstring("\txchg ");
                emit_register(in1, NULL);
                be_emit_cstring(", ");
                emit_register(in0, NULL);
                be_emit_finish_line_gas(node);
        } else if (cls0 == &ia32_reg_classes[CLASS_ia32_xmm]) {
                be_emit_cstring("\txorpd ");
                emit_register(in1, NULL);
                be_emit_cstring(", ");
                emit_register(in0, NULL);
                be_emit_finish_line_gas(NULL);

                be_emit_cstring("\txorpd ");
                emit_register(in0, NULL);
                be_emit_cstring(", ");
                emit_register(in1, NULL);
                be_emit_finish_line_gas(NULL);

                be_emit_cstring("\txorpd ");
                emit_register(in1, NULL);
                be_emit_cstring(", ");
                emit_register(in0, NULL);
                be_emit_finish_line_gas(node);
        } else if (cls0 == &ia32_reg_classes[CLASS_ia32_vfp]) {
                /* is a NOP */
        } else if (cls0 == &ia32_reg_classes[CLASS_ia32_st]) {
                /* is a NOP */
        } else {
                panic("unexpected register class in be_Perm (%+F)\n", node);
        }
}

/**
 * Emits code for Constant loading.
 */
static void emit_ia32_Const(const ir_node *node)
{
        be_emit_cstring("\tmovl ");
        emit_ia32_Immediate(node);
        be_emit_cstring(", ");
        ia32_emit_dest_register(node, 0);

        be_emit_finish_line_gas(node);
}

/**
 * Emits code to load the TLS base
 */
static void emit_ia32_LdTls(const ir_node *node)
{
        be_emit_cstring("\tmovl %gs:0, ");
        ia32_emit_dest_register(node, 0);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_mov(const ir_node* node, const arch_register_t *src, const arch_register_t *dst)
{
        be_emit_cstring("\tmovl ");
        emit_register(src, NULL);
        be_emit_cstring(", ");
        emit_register(dst, NULL);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_neg(const ir_node* node, const arch_register_t *reg)
{
        be_emit_cstring("\tnegl ");
        emit_register(reg, NULL);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_sbb0(const ir_node* node, const arch_register_t *reg)
{
        be_emit_cstring("\tsbbl $0, ");
        emit_register(reg, NULL);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_sbb(const ir_node* node, const arch_register_t *src, const arch_register_t *dst)
{
        be_emit_cstring("\tsbbl ");
        emit_register(src, NULL);
        be_emit_cstring(", ");
        emit_register(dst, NULL);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_xchg(const ir_node* node, const arch_register_t *src, const arch_register_t *dst)
{
        be_emit_cstring("\txchgl ");
        emit_register(src, NULL);
        be_emit_cstring(", ");
        emit_register(dst, NULL);
        be_emit_finish_line_gas(node);
}

/* helper function for emit_ia32_Minus64Bit */
static void emit_zero(const ir_node* node, const arch_register_t *reg)
{
        be_emit_cstring("\txorl ");
        emit_register(reg, NULL);
        be_emit_cstring(", ");
        emit_register(reg, NULL);
        be_emit_finish_line_gas(node);
}

static void emit_ia32_Minus64Bit(const ir_node *node)
{
        const arch_register_t *in_lo  = get_in_reg(node, 0);
        const arch_register_t *in_hi  = get_in_reg(node, 1);
        const arch_register_t *out_lo = get_out_reg(node, 0);
        const arch_register_t *out_hi = get_out_reg(node, 1);

        if (out_lo == in_lo) {
                if (out_hi != in_hi) {
                        /* a -> a, b -> d */
                        goto zero_neg;
                } else {
                        /* a -> a, b -> b */
                        goto normal_neg;
                }
        } else if (out_lo == in_hi) {
                if (out_hi == in_lo) {
                        /* a -> b, b -> a */
                        emit_xchg(node, in_lo, in_hi);
                        goto normal_neg;
                } else {
                        /* a -> b, b -> d */
                        emit_mov(node, in_hi, out_hi);
                        emit_mov(node, in_lo, out_lo);
                        goto normal_neg;
                }
        } else {
                if (out_hi == in_lo) {
                        /* a -> c, b -> a */
                        emit_mov(node, in_lo, out_lo);
                        goto zero_neg;
                } else if (out_hi == in_hi) {
                        /* a -> c, b -> b */
                        emit_mov(node, in_lo, out_lo);
                        goto normal_neg;
                } else {
                        /* a -> c, b -> d */
                        emit_mov(node, in_lo, out_lo);
                        goto zero_neg;
                }
        }

normal_neg:
        emit_neg( node, out_hi);
        emit_neg( node, out_lo);
        emit_sbb0(node, out_hi);
        return;

zero_neg:
        emit_zero(node, out_hi);
        emit_neg( node, out_lo);
        emit_sbb( node, in_hi, out_hi);
}

static void emit_be_Return(const ir_node *node)
{
        unsigned pop;
        be_emit_cstring("\tret");

        pop = be_Return_get_pop(node);
        if(pop > 0) {
                be_emit_irprintf(" $%d", pop);
        }
        be_emit_finish_line_gas(node);
}

static void emit_Nothing(const ir_node *node)
{
        (void) node;
}


/***********************************************************************************
 *                  _          __                                             _
 *                 (_)        / _|                                           | |
 *  _ __ ___   __ _ _ _ __   | |_ _ __ __ _ _ __ ___   _____      _____  _ __| | __
 * | '_ ` _ \ / _` | | '_ \  |  _| '__/ _` | '_ ` _ \ / _ \ \ /\ / / _ \| '__| |/ /
 * | | | | | | (_| | | | | | | | | | | (_| | | | | | |  __/\ V  V / (_) | |  |   <
 * |_| |_| |_|\__,_|_|_| |_| |_| |_|  \__,_|_| |_| |_|\___| \_/\_/ \___/|_|  |_|\_\
 *
 ***********************************************************************************/

/**
 * Enters the emitter functions for handled nodes into the generic
 * pointer of an opcode.
 */
static
void ia32_register_emitters(void) {

#define IA32_EMIT2(a,b) op_ia32_##a->ops.generic = (op_func)emit_ia32_##b
#define IA32_EMIT(a)    IA32_EMIT2(a,a)
#define EMIT(a)         op_##a->ops.generic = (op_func)emit_##a
#define IGN(a)                  op_##a->ops.generic = (op_func)emit_Nothing
#define BE_EMIT(a)      op_be_##a->ops.generic = (op_func)emit_be_##a
#define BE_IGN(a)               op_be_##a->ops.generic = (op_func)emit_Nothing

        /* first clear the generic function pointer for all ops */
        clear_irp_opcodes_generic_func();

        /* register all emitter functions defined in spec */
        ia32_register_spec_emitters();

        /* other ia32 emitter functions */
        IA32_EMIT(Asm);
        IA32_EMIT(CMov);
        IA32_EMIT(IMul);
        IA32_EMIT(SwitchJmp);
        IA32_EMIT(CopyB);
        IA32_EMIT(CopyB_i);
        IA32_EMIT(Conv_I2FP);
        IA32_EMIT(Conv_FP2I);
        IA32_EMIT(Conv_FP2FP);
        IA32_EMIT(Conv_I2I);
        IA32_EMIT2(Conv_I2I8Bit, Conv_I2I);
        IA32_EMIT(Const);
        IA32_EMIT(LdTls);
        IA32_EMIT(Minus64Bit);
        IA32_EMIT(Jcc);

        /* benode emitter */
        BE_EMIT(Call);
        BE_EMIT(IncSP);
        BE_EMIT(Copy);
        BE_EMIT(CopyKeep);
        BE_EMIT(Perm);
        BE_EMIT(Return);

        BE_IGN(RegParams);
        BE_IGN(Barrier);
        BE_IGN(Keep);

        /* firm emitter */
        EMIT(Jmp);
        IGN(Proj);
        IGN(Phi);
        IGN(Start);

#undef BE_EMIT
#undef EMIT
#undef IGN
#undef IA32_EMIT2
#undef IA32_EMIT
}

static const char *last_name = NULL;
static unsigned last_line = -1;
static unsigned num = -1;

/**
 * Emit the debug support for node node.
 */
static void ia32_emit_dbg(const ir_node *node)
{
        dbg_info *db = get_irn_dbg_info(node);
        unsigned lineno;
        const char *fname = ir_retrieve_dbg_info(db, &lineno);

        if (! cg->birg->main_env->options->stabs_debug_support)
                return;

        if (fname) {
                if (last_name != fname) {
                        last_line = -1;
                        be_dbg_include_begin(cg->birg->main_env->db_handle, fname);
                        last_name = fname;
                }
                if (last_line != lineno) {
                        char name[64];

                        snprintf(name, sizeof(name), ".LM%u", ++num);
                        last_line = lineno;
                        be_dbg_line(cg->birg->main_env->db_handle, lineno, name);
                        be_emit_string(name);
                        be_emit_cstring(":\n");
                        be_emit_write_line();
                }
        }
}

typedef void (*emit_func_ptr) (const ir_node *);

/**
 * Emits code for a node.
 */
static void ia32_emit_node(const ir_node *node)
{
        ir_op *op = get_irn_op(node);

        DBG((dbg, LEVEL_1, "emitting code for %+F\n", node));

        if (op->ops.generic) {
                emit_func_ptr func = (emit_func_ptr) op->ops.generic;
                ia32_emit_dbg(node);
                (*func) (node);
        } else {
                emit_Nothing(node);
                ir_fprintf(stderr, "Error: No emit handler for node %+F (%+G, graph %+F)\n", node, node, current_ir_graph);
                abort();
        }
}

/**
 * Emits gas alignment directives
 */
static void ia32_emit_alignment(unsigned align, unsigned skip)
{
        be_emit_cstring("\t.p2align ");
        be_emit_irprintf("%u,,%u\n", align, skip);
        be_emit_write_line();
}

/**
 * Emits gas alignment directives for Functions depended on cpu architecture.
 */
static void ia32_emit_align_func(void)
{
        unsigned align        = ia32_cg_config.function_alignment;
        unsigned maximum_skip = (1 << align) - 1;

        ia32_emit_alignment(align, maximum_skip);
}

/**
 * Emits gas alignment directives for Labels depended on cpu architecture.
 */
static void ia32_emit_align_label(void)
{
        unsigned align        = ia32_cg_config.label_alignment;
        unsigned maximum_skip = (1 << align) - 1;
        ia32_emit_alignment(align, maximum_skip);
}

/**
 * Test wether a block should be aligned.
 * For cpus in the P4/Athlon class it is useful to align jump labels to
 * 16 bytes. However we should only do that if the alignment nops before the
 * label aren't executed more often than we have jumps to the label.
 */
static int should_align_block(ir_node *block, ir_node *prev)
{
        static const double DELTA = .0001;
        ir_exec_freq *exec_freq   = cg->birg->exec_freq;
        double        block_freq;
        double        prev_freq = 0;  /**< execfreq of the fallthrough block */
        double        jmp_freq  = 0;  /**< execfreq of all non-fallthrough blocks */
        int           i, n_cfgpreds;

        if(exec_freq == NULL)
                return 0;
        if(ia32_cg_config.label_alignment_factor <= 0)
                return 0;

        block_freq = get_block_execfreq(exec_freq, block);
        if(block_freq < DELTA)
                return 0;

        n_cfgpreds = get_Block_n_cfgpreds(block);
        for(i = 0; i < n_cfgpreds; ++i) {
                ir_node *pred      = get_Block_cfgpred_block(block, i);
                double   pred_freq = get_block_execfreq(exec_freq, pred);

                if(pred == prev) {
                        prev_freq += pred_freq;
                } else {
                        jmp_freq  += pred_freq;
                }
        }

        if(prev_freq < DELTA && !(jmp_freq < DELTA))
                return 1;

        jmp_freq /= prev_freq;

        return jmp_freq > ia32_cg_config.label_alignment_factor;
}

static void ia32_emit_block_header(ir_node *block, ir_node *prev)
{
        int           n_cfgpreds;
        int           need_label;
        int           i, arity;
        ir_exec_freq  *exec_freq = cg->birg->exec_freq;

        n_cfgpreds = get_Block_n_cfgpreds(block);
        need_label = (n_cfgpreds != 0);

        if (should_align_block(block, prev)) {
                assert(need_label);
                ia32_emit_align_label();
        }

        if(need_label) {
                ia32_emit_block_name(block);
                be_emit_char(':');

                be_emit_pad_comment();
                be_emit_cstring("   /* preds:");

                /* emit list of pred blocks in comment */
                arity = get_irn_arity(block);
                for (i = 0; i < arity; ++i) {
                        ir_node *predblock = get_Block_cfgpred_block(block, i);
                        be_emit_irprintf(" %d", get_irn_node_nr(predblock));
                }
        } else {
                be_emit_cstring("\t/* ");
                ia32_emit_block_name(block);
                be_emit_cstring(": ");
        }
        if (exec_freq != NULL) {
                be_emit_irprintf(" freq: %f",
                                 get_block_execfreq(exec_freq, block));
        }
        be_emit_cstring(" */\n");
        be_emit_write_line();
}

/**
 * Walks over the nodes in a block connected by scheduling edges
 * and emits code for each node.
 */
static void ia32_gen_block(ir_node *block, ir_node *last_block)
{
        const ir_node *node;

        ia32_emit_block_header(block, last_block);

        /* emit the contents of the block */
        ia32_emit_dbg(block);
        sched_foreach(block, node) {
                ia32_emit_node(node);
        }
}

/**
 * Emits code for function start.
 */
static void ia32_emit_func_prolog(ir_graph *irg)
{
        ir_entity  *irg_ent  = get_irg_entity(irg);
        const char *irg_name = get_entity_ld_name(irg_ent);
        const be_irg_t *birg = cg->birg;

        /* write the begin line (used by scripts processing the assembler... */
        be_emit_write_line();
        be_emit_cstring("# -- Begin  ");
        be_emit_string(irg_name);
        be_emit_char('\n');
        be_emit_write_line();

        be_gas_emit_switch_section(GAS_SECTION_TEXT);
        be_dbg_method_begin(birg->main_env->db_handle, irg_ent, be_abi_get_stack_layout(birg->abi));
        ia32_emit_align_func();
        if (get_entity_visibility(irg_ent) == visibility_external_visible) {
                be_emit_cstring(".global ");
                be_emit_string(irg_name);
                be_emit_char('\n');
                be_emit_write_line();
        }
        ia32_emit_function_object(irg_name);
        be_emit_string(irg_name);
        be_emit_cstring(":\n");
        be_emit_write_line();
}

/**
 * Emits code for function end
 */
static void ia32_emit_func_epilog(ir_graph *irg)
{
        const char     *irg_name = get_entity_ld_name(get_irg_entity(irg));
        const be_irg_t *birg     = cg->birg;

        ia32_emit_function_size(irg_name);
        be_dbg_method_end(birg->main_env->db_handle);

        be_emit_cstring("# -- End  ");
        be_emit_string(irg_name);
        be_emit_char('\n');
        be_emit_write_line();

        be_emit_char('\n');
        be_emit_write_line();
}

/**
 * Block-walker:
 * Sets labels for control flow nodes (jump target)
 */
static void ia32_gen_labels(ir_node *block, void *data)
{
        ir_node *pred;
        int n = get_Block_n_cfgpreds(block);
        (void) data;

        for (n--; n >= 0; n--) {
                pred = get_Block_cfgpred(block, n);
                set_irn_link(pred, block);
        }
}

/**
 * Emit an exception label if the current instruction can fail.
 */
void ia32_emit_exc_label(const ir_node *node)
{
        if (get_ia32_exc_label(node)) {
                be_emit_irprintf(".EXL%u\n", 0);
                be_emit_write_line();
        }
}

/**
 * Main driver. Emits the code for one routine.
 */
void ia32_gen_routine(ia32_code_gen_t *ia32_cg, ir_graph *irg)
{
        ir_node *block;
        ir_node *last_block = NULL;
        int i, n;

        cg       = ia32_cg;
        isa      = (const ia32_isa_t*) cg->arch_env->isa;
        arch_env = cg->arch_env;

        ia32_register_emitters();

        ia32_emit_func_prolog(irg);
        irg_block_walk_graph(irg, ia32_gen_labels, NULL, NULL);

        n = ARR_LEN(cg->blk_sched);
        for (i = 0; i < n;) {
                ir_node *next_bl;

                block   = cg->blk_sched[i];
                ++i;
                next_bl = i < n ? cg->blk_sched[i] : NULL;

                /* set here the link. the emitter expects to find the next block here */
                set_irn_link(block, next_bl);
                ia32_gen_block(block, last_block);
                last_block = block;
        }

        ia32_emit_func_epilog(irg);
}

void ia32_init_emitter(void)
{
        FIRM_DBG_REGISTER(dbg, "firm.be.ia32.emitter");
}